PSA screening for prostate cancer saves lives after all

After years of growing doubt about the value of screening men for prostate cancer, a new analysis of existing clinical trial evidence has found that when men between 55 and 70 get the prostate-specific antigen, or PSA, test, the result is lives saved.

In 2009, a New England Journal of Medicine editorialist famously called the debate over PSA testing for prostate cancer “the controversy that refuses to die”. That comment came with the publication of two clinical trials — one conducted in the United States, the second in Europe — that drew two contradictory conclusions on prostate cancer testing.

The US undertaking, called the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, found that screening men for prostate cancer does not save lives. The European Randomised Study of Screening for Prostate Cancer suggested that screening drove down the rate of deaths from prostate cancer by 20 per cent.

In 2012, a federally funded panel of experts on preventive care concluded there are more risks than benefits to screening American men for prostate cancer with the PSA test. And in April 2017, the US Preventive Services Task Force dumped the decision squarely into the laps of patients and their doctors. Some men between 55 and 69 years of age might well decide to get their PSA checked, the task force said. After hearing the ledger of pros and cons, however, others in that age bracket might just as reasonably skip the screening test, the panel concluded.

The new research, published this week in the Annals of Internal Medicine, now calls those recommendations into question. The authors of the study, led by biostatistician Ruth Etzioni of Fred Hutchinson Cancer Research Centre in Seattle, concluded that screening men over age 55 “can significantly reduce the risk for prostate cancer death”.

When men who fit the criteria for screening get the PSA test, the reduction in deaths due to prostate cancer was between 25 per cent and 32 per cent, the new study found.

But the newly published analysis also underscores that the value of prostate cancer screening rests heavily on which men you screen, where and for how long you conduct the clinical trial and how you crunch the numbers.

In the end, said Vanderbilt University urological surgeon Dr Sam Chang, the new analysis “reinforces what urological surgeons and treating physicians have thought all along: that PSA screening is helpful”.

But it is helpful, said Chang, only when it focuses on the right men — those between 55 and 70 — and when it is tempered by an understanding that not all worrisome findings are evidence of disease that should be treated aggressively.

Sometimes, said Chang, who was not involved in the newly published article, a man will get a problematic PSA test reading and decide not to act on it immediately or aggressively. But knowing there is a decision to be made is probably a better basis for planning than not knowing, he added.

“Over the past five to 10 years, there has been a better understanding by everyone about the harms of over-treatment,” Chang said. “You want to avoid over-diagnosis and over-treatment.”

Chang underscored that for two groups in particular — African American men and those with a first-degree relative who died of prostate cancer — knowing is especially important, because the risks of aggressive disease in such populations is much higher than for others. Neither group was the subject of special attention in the newly published analysis.

In an editorial published Monday alongside the new analysis, Andrew Vickers of Memorial Sloan Kettering Cancer Centre also made clear that it’s what patients and their physicians do after the PSA test that matters most.

“Unfortunately, the way screening has been implemented in the United States leaves much to be desired,” Vickers wrote. “The controversy about PSA-based screening should no longer be whether it can do good but whether we can change our behaviour so that it does more good than harm,” he added.

Prostate cancer is the most common non-skin cancer found in men, affecting 101.6 of 100,000 American men, according to the Centres for Disease Control & Prevention. In 2013, the latest year for which figures are available, 176,000 got a diagnosis of prostate cancer and 28,000 died of it.

But a change in a man’s reading on the PSA test is a highly imperfect gauge of trouble: approximately 80 per cent of positive PSA test results are thought to produce false-positives, creating scares that prompt men to get biopsies. And treatment, which carries with it a high risk of subsequent difficulties with sexual function, urination and bowel movements, is often unnecessary because prostate cancers are often so slow-growing they will never make a man sick.

A Canadian study that many experts say has major flaws has revived debate about the value of mammograms. The research suggests that these screening X-rays do not lower the risk of dying of breast cancer while finding many tumours that do not need treatment.

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